This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2002-189719, filed Jun. 28, 2002, the entire contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a pipe coupling for fluid, the coupling comprises a socket and a plug that can be connected to each other.
2. Description of the Related Art
Conventionally, a pipe coupling of this type comprises a plug body and a socket. The plug has a distal end portion, an axial bore opening in the distal end portion, and an outer peripheral portion on which a projection is formed. The socket is connected to the plug body. It is provided with a main cylinder having an axial bore, which extends between first and second end portions and through which a fluid can flow.
The socket of the pipe coupling comprises a ball valve and an annular seal unit. The ball valve has a through bore formed having one end capable of receiving the distal end portion of the plug body and the other end portion capable of communicating with the axial bore. The ball valve is located at a first end portion of the main cylinder and controls the axial bore in an open-close condition. The seal unit is located near the first end portion in the axial bore and has a distal end portion formed having a ball valve receiving surface in sealed engagement with the ball valve. In order to support the ball valve in conjunction with the ball valve receiving surface, moreover, the socket comprises a casing, which has a base portion fixed to the first end portion of the main cylinder, a top portion opposed to the base portion, a flank portion located between the first end portion and the top portion, and a slot extending from the flank portion to the top portion. The slot has a flank opening and a top opening. When the other end of the through bore is disconnected from the axial bore of the main cylinder, the flank opening is aligned with the one end of the through bore, and the projection of the plug body can be passed through the flank opening. When the other end of the through bore communicates with the axial bore of the main cylinder, the top opening is aligned with the one end of the through bore and engages the projection. Thus, the ball valve can be rocked by the plug body in the one end of the through bore between a position in which the other end of the through bore communicates with the axial bore of the main cylinder and a position in which the other end is disconnected from the axial bore.
According to the pipe coupling constructed in this manner, however, the ball valve that is surrounded by the casing and supported by the main cylinder is rockable, and it is not in any way restricted in its rocking motion. If a shock acts on the socket that is not connected with the plug, from any cause, for example, the ball valve may rock under the influence of the shock, in some cases, so that the through bore fails to be opposed to the slot of the casing; that is, it is disengaged from the slot. Accordingly, it is hard to insert the plug body into the through bore of the valve through the slot of the casing. In other cases, the through bore may unexpectedly communicate with the fluid passage of the main cylinder as the ball valve rocks, or the valve may open. As long as the outside diameter of the plug body is smaller than the diameter of the through bore of the ball valve, moreover, the plug body can be inserted into the through bore. Thus, a wrong plug can inevitably be inserted into the through bore of the ball valve to rock the valve, thereby opening the through bore.
The object of the present invention is to provide a pipe coupling in which the movement of a ball valve is restricted when a plug is not connected, so that the plug can be connected securely, wrong operation of the ball valve can be prevented, and the connected plug never fails to be an appropriate one.
In order to achieve the above object of the present invention, there is provided a pipe coupling which comprises a plug body having a distal end portion, an axial bore opening in the distal end portion, and an outer peripheral portion on which a projection is formed, and a socket main cylinder having first and second end portions and an axial bore which extends between the end portions and through which a fluid can flow. Further, the pipe coupling comprises a ball valve which has a through bore formed having one end capable of receiving the distal end portion of the plug body and the other end portion capable of communicating with the axial bore, is located at a first end portion of the socket main cylinder, and controls the axial bore in an open-close condition; an annular seal unit located near the first end portion in the axial bore and having a distal end portion formed having a ball valve receiving surface in sealed engagement with the ball valve; and a casing which has a base portion fixed to the first end portion of the socket main cylinder, a top portion opposed to the base portion, a flank portion located between the first end portion and the top portion, and a slot extending from the flank portion to the top portion and which supports the ball valve in conjunction with the ball valve receiving surface. The slot has a flank opening, which is aligned with the one end of the through bore and through which the projection of the plug body can be passed when the other end of the through bore is disconnected from the axial bore of the socket main cylinder, and a top opening, which is aligned with the one end of the through bore and engages the projection when the other end of the through bore communicates with the axial bore of the socket main cylinder, so that the ball valve is rocked by the plug body in the one end of the through bore between a position in which the other end of the through bore communicates with the axial bore of the socket main cylinder and a position in which the other end is disconnected from the axial bore. The pipe coupling of the invention further comprises a lock element located for reciprocation in the through bore of the ball valve, the lock element being urged toward the one end and adapted to move into the flank opening to prevent the ball valve from rocking with respect to the casing when the one end of the through bore of the ball valve is aligned with the flank opening and to move into the through bore of the ball valve to allow the ball valve to rock with respect to the casing when the plug body is inserted into the one end of the through bore.
According to this pipe coupling, the lock element in the through bore of the ball valve advances urged by a spring and projects into the flank opening when the one end of the through bore is aligned with a position on the flank opening side of the slot of the casing. The lock element can engage the peripheral end edge of the slot on the top opening side. If a force to rock the ball valve acts from any cause in this state, the advanced lock element engages the peripheral end edge of the flank opening, thereby preventing the valve from rocking. Thus, the through bore of the ball valve is kept ready for the passage of the plug, and the valve is prevented from opening. If the plug body is inserted into the through bore of the ball valve in connecting the plug, the advanced lock element is pushed by the plug and retreats. Thereupon, it is disengaged from the peripheral end edge of the flank opening, thereby allowing the ball valve to rock. Thus, the plug and the socket can be connected by rocking the plug body in the through bore of the valve from the flank opening of the slot. The plug can be disconnected from the socket by rocking the plug body toward the flank opening of the slot with the lock element being retreated and then drawing it out of the through bore of the ball valve. When the plug is drawn out of the through bore of the valve, the lock element advances urged by the spring and engages with the flank opening of the slot, whereupon the valve is prevented from rocking. Thus, the through bore of the ball valve is kept ready for the passage of the plug, so that the plug can be reconnected securely.
According to the pipe coupling of the invention, therefore, the lock element prevents the ball valve of the socket from rocking when the plug is not connected to the socket. If a shock acts on the socket from any cause, thereby urging the ball valve to rock, the through bore of the ball valve is kept opened on the flank opening side so that the plug can be passed through it. Thus, the ball valve can be securely prevented from rocking and hindering the connection of the plug or from opening.
Preferably, the lock element comprises a cylindrical element, having an outer peripheral portion smaller in diameter than the flank opening and an inner peripheral portion larger in diameter than the distal end portion of the plug body, and a retaining step portion protruding from the outer peripheral portion of the cylindrical element and having a diameter larger than that of the flank opening. And more preferably, the lock element has a retaining step portion inwardly protruding from the inner peripheral portion and capable of engaging the projection of the plug body.
In this case, the outside diameter and the shape of the outer peripheral surface of the plug body are restricted by the inside diameter and the shape of the inner peripheral surface of the cylindrical lock element that is slidable in the through bore of the ball valve. Thus, the plug to be connected can be specified, so that improper plug connection can be prevented.
Preferably, moreover, the axial bore is formed of a stepped bore having a large-diameter portion and a small-diameter portion, and the seal unit has an annular seal holding member located in the large-diameter portion for axial movement, a collar located in the seal holding member for axial movement, and a seal ring located between the seal holding member and the collar and in sealed engagement with the ball valve.
Preferably, the casing has a fitting projection protruding from the peripheral portion of the top opening, and the plug body has a lock member which is stopped by the fitting projection to prevent the movement of the ball valve when the ball valve is rocked from the position in which the other end of the through bore is disconnected from the axial bore of the socket main cylinder to the position in which the other end communicates with the axial bore. Preferably, moreover, the lock member is urged toward the distal end portion of the plug body.
According to the present invention, moreover, there is provided a socket which forms a pipe coupling in conjunction with a plug having a distal end portion, an axial bore opening in the distal end portion, and an outer peripheral portion on which a projection is formed. The socket comprises a main cylinder having first and second end portions and an axial bore which extends between the end portions and through which a fluid can flow; a ball valve which has a through bore formed having one end capable of receiving the distal end portion of the plug and the other end portion capable of communicating with the axial bore, is located at a first end portion of the main cylinder, and controls the axial bore in an open-close condition; an annular seal unit located near the first end portion in the axial bore and having a distal end portion formed having a ball valve receiving surface in sealed engagement with the ball valve; and a casing which has a base portion fixed to the first end portion of the main cylinder, a top portion opposed to the base portion, a flank portion located between the first end portion and the top portion, and a slot extending from the flank portion to the top portion and which supports the ball valve in conjunction with the ball valve receiving surface. The slot has a flank opening, which is aligned with the one end of the through bore and through which the projection of the plug can be passed when the other end of the through bore is disconnected from the axial bore of the main cylinder, and a top opening, which is aligned with the one end of the through bore and engages the projection when the other end of the through bore communicates with the axial bore of the main cylinder, so that the ball valve is rocked by the plug in the one end of the through bore between a position in which the other end of the through bore communicates with the axial bore of the main cylinder and a position in which the other end is disconnected from the axial bore. Further, the socket comprises a lock element located for reciprocation in the through bore of the ball valve, the lock element being urged toward the one end and adapted to move into the flank opening to prevent the ball valve from rocking with respect to the casing when the one end of the through bore of the ball valve is aligned with the flank opening and to move into the through bore of the ball valve to allow the ball valve to rock with respect to the casing when the plug is inserted into the one end of the through bore.